Generally, to connect an ITO electrode formed on a glass substrate of a liquid crystal panel with a TAB having a driving IC mounted thereon, or to connect a flexible wiring board of a liquid crystal display device with a printed wiring board, an anisotropic conductive film has been widely used which is produced by forming into a film shape a thermosetting resin composition containing a thermosetting epoxy resin, a polymerization initiator, and conductive particles. Normally, in such a case, the temperature for compression bonding is approximately 180° C. to 250° C., and the time for compression bonding is approximately 5 seconds to 10 seconds.
In recent years, in order to reduce thermal stress on an electrode portion of a flexible board or on an ITO electrode on a glass substrate of a liquid crystal panel, a reduction in compression bonding temperature during thermo-compression bonding using an anisotropic conductive film is required. Moreover, in order not only to reduce the thermal stress but also to improve production efficiency, a reduction in compression bonding time is required. To meet these requirements, an attempt has been made to use, instead of the thermosetting epoxy resin constituting the anisotropic conductive film, a polymerizable acrylic compound together with a film-forming resin, the polymerizable acrylic compound being capable of curing at a lower temperature in a shorter time than the thermosetting epoxy resin. In such a case, it has been proposed to use as a polymerization initiator an organic peroxide that does not produce gas as the self decomposition thereof proceeds (Patent Document 1). Specifically, an organic peroxide having a relatively low one-minute half-life temperature of approximately 100° C. to 130° C. is used. (Examples thereof include dibenzoyl peroxide (one-minute half-life temperature: 130° C.), dilauroyl peroxide (one-minute half-life temperature: 116.4° C.), and di-(3,5,5,-trimethylhexanoyl) peroxide (one-minute half-life temperature: 112.6° C.).)    [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-199825.